Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$101.73	3.158%	$104.9426	$104.94	$104.95	$104.90
Purchase #2	$80.91	3.554%	$83.7855	$83.79	$83.80	$83.80
Purchase #3	$141.88	10.377%	$156.6029	$156.60	$156.60	$156.60
Purchase #4	$99.30	10.716%	$109.941	$109.94	$109.95	$109.90
Purchase #5	$102.94	5.427%	$108.5266	$108.53	$108.55	$108.50
Purchase #6	$232.90	8.773%	$253.3323	$253.33	$253.35	$253.30
Purchase #7	$141.95	4.542%	$148.3974	$148.40	$148.40	$148.40
7 purchase totals =	$901.61		$965.5283	$965.53	$965.60	$965.40